Periodic limb movement disorder involves repetitive movements of the arms, legs, or both during sleep. Restless legs syndrome involves an irresistible urge to move and usually abnormal sensations in the legs, arms, or both when people sit still or lie down.
In people with periodic limb movement disorders, the legs, arms, or both twitch and jerk, disrupting sleep, but people are usually not aware of the movements.
People with restless legs syndrome have trouble relaxing and sleeping because they feel an irresistible urge to move their legs or arms.
Doctors may diagnose restless legs syndrome based on symptoms, but testing in a sleep laboratory is needed to diagnose periodic limb movement disorder.
There is no cure, but medications used to treat Parkinson disease and other medications may help control symptoms.
These sleep disorders are more common during middle and older age.
In the United States, restless legs syndrome may affect 5 to 15% of people, but only about 2 to 3% have significant symptoms. Most people with restless legs syndrome also have symptoms of periodic limb movement disorder, but most people with periodic limb movement disorder do not have restless legs syndrome.
What causes restless legs syndrome and periodic limb movement disorder is unknown. But one third or more of people with restless legs syndrome have family members with the syndrome. Risk factors include the following:
A sedentary lifestyle
Smoking
Obesity
Periodic limb movement disorder is more common during middle and older age. It commonly occurs in people with narcolepsy or rapid eye movement (REM) sleep behavior disorder.
Both restless legs syndrome and periodic limb movement disorder are more likely in people who have or do the following:
Have iron deficiency
Have anemia
Are pregnant
Have a severe chronic kidney or liver disorder
Have diabetes
Have a neurologic disorder, such as multiple sclerosis or Parkinson disease
Symptoms of PLMD and RLS
Both periodic limb movement disorder and restless legs syndrome interrupt sleep. As a result, people feel tired and sleepy during the day.
Symptoms of periodic limb movement disorder
The legs or arms typically twitch and jerk every 20 to 40 seconds during sleep. People are usually unaware of these movements and the brief awakenings that follow, but they may complain of sleeping poorly, waking up several times during the night, or feeling sleepy during the day. People do not have any abnormal sensations in their legs or arms. Bed partners may complain about being kicked.
Symptoms of restless legs syndrome
Typically, people with restless legs syndrome have an irresistible urge to move their legs when they are sitting still or lying down. People also often feel vague but intense strange sensations in their legs, sometimes accompanied by pain. The sensations may be described as burning, creeping, or tugging or like insects crawling inside the legs.
Walking or moving or stretching the legs can relieve the sensations. People may pace, constantly move their legs while they are sitting, and toss and turn in bed. Thus, people have difficulty relaxing and falling asleep. During sleep, the legs may move spontaneously and uncontrollably, often awakening the sleeper.
Symptoms are more likely to occur when people are under stress. Episodes may occur occasionally, causing few problems, or daily, depriving people of sleep and making it difficult to concentrate and function.
Diagnosis of PLMD and RLS
For restless legs syndrome, a doctor's evaluation
For periodic limb movement disorder, polysomnography
For either disorder, tests to check for a cause
Doctors can often diagnose restless legs syndrome based on symptoms reported by the person or the person’s bed partner. Doctors may suspect periodic limb movement disorder based on symptoms, such as insomnia, excessive daytime sleepiness, and/or excessive twitching just before going to sleep or during sleep.
Polysomnography, including electromyography (EMG), is always done to diagnose periodic limb movement disorder. These tests are done overnight in a sleep laboratory and are not done at home. In polysomnography, brain activity, heart rate, breathing, muscle activity, and eye movements are monitored while people sleep. People may also be videotaped during an entire night's sleep to document limb movements. These tests may also be done after restless legs syndrome is diagnosed to determine whether people also have periodic limb movement disorder.
If either disorder is diagnosed, blood and urine tests are done to check for disorders that can contribute, such as anemia, iron deficiency, and kidney and liver disorders.
Treatment of PLMD and RLS
Changes in the diet
Medications, including some that are used to treat Parkinson diseases
Avoiding caffeine, which can make symptoms worse, is recommended. If people are deficient in iron, the primary treatment is iron supplements.
The same medications are used to treat periodic limb movement disorder and restless legs syndrome. These medications include
Medications typically used to treat Parkinson disease:dopamine—a chemical that transmits messages from nerve cells to other cells (neurotransmitter). They increase nerve impulses to muscles. Sometimes these medications cause symptoms to worsen. They can also cause nausea, an excessive decrease in blood pressure when a person stands (orthostatic hypotension), compulsive behaviors, and insomnia.
Gabapentin enacarbil is the main treatment for people with periodic limb movement disorder or restless leg syndrome. This medication relieves symptoms of restless legs syndrome and does not cause symptoms to worsen.
